ABC Cocina and ABC Kitchen are at the top of my list of local favourite restaurants. Located in the Flatiron District, they are a short walk from Madison Square Park. Both restaurants focus on fresh, local and seasonal ingredients, with ABC Cocina being a more Latin tapas style restaurant and ABC Kitchen being more chic/classic/up-town. Both have GORGEOUS interiors. Both are particularly expensive and particularly busy, I recommend booking a table well in advance (or do as we do and rock up, put your name on the list and be prepared to wait a while for a table or a spot at the bar).
Madison Square Park & ABC Cocina: